No, it is not, and it never was. The UK billion was a million million,i.e. a US trillion. 1000 million, the equivalent of the US billion, wasthe milliard. However, US-style usage is becoming more prevalent in the UK, just as many people today say "radio" and no longer "wireless".

In other languages, terms similar to the old UK usage are the only ones in use, e.g. German has Milliarde for 1000 million and Billion for one million million.